Armature



April 25, 1950 w. F. ALLENBY 2,505,026

ARMATURE Original Filed Aug. 31,' 1944 A WM5/v5 Patented Apr.l 25, 1950ARMATUBE William F. Allenby, Stratford, Conn., assigner to CascoProducts Corporation, Bridgeport, Conn., a corporation of Connecticut`Original application August 31, 1944, Serial No. 552,185. Divided andthis application May 10, 1946, Serial N0. 668,798

1 This invention relates to small handheld electric power tools, andmore particularly to improvements in the armature of the motor thereof.`

This application is a divison of my application, Serial No. 552,185,filed August 31. 1944 which issued as Patent No. 2,436,540 on February24, 1948.

It is an object of the present invention to provide means for preventingthe leads extending from the armature coils to the commutators fromvibrating excessively and breaking loose their solder connection to thecommutators.

This is accomplished according to the present invention by providing arigidly mounted supporting band between the commutator and armaturecoils to which band the lead wires from the armature are bound. Inthe'illustrated embodiment of the invention the supporting band is madeas an integral part of the molded commutator body, so that the leadwires may be secured to the commutator structure by a strongvibration-resistant binding in addition to the soldered electricalconnections commonly employed, which latter', if not reinforced byadditional means, often work loose when subjected to vibrating forcesbecause of variations in soldering technique and skill employed.

Other features and advantages will hereinafter appear.

In the accompanying drawing:

The gure shows a view partly in section of the armature.

Referring to the drawing, the motor of the present invention has anarmature III and a disk commutator II, the latter being engaged bybrushes I2. The motor has a eld structure I3 overlying the sides thereofand provided with a. ileld coil, not shown, for cooperating with thearmature. `f

The motor is mounted in a subframe I4 disposed within a casing I5. Thearmature I of the motor is carried by a shaft I6 journaled in bearingsleeves II and I8, the latter being press fitted into the portion Ila ofthe subframe. The subframe I4 is provided with a pair of recesses llc inwhich the brushes I2 are carried, the latter being press tted into therecesses with strip insulation I 9, as shown in the drawings.Accordingly, the brushes I2 will be maintained in accurate alignmentregardless of the working stresses existing in the motor since thebrushes are carried by a rigid cast metal.

At the lower end of the shaft I6 an improved wear-resistant thrustbearing is provided in the form of a hardened steel ball 20 having adiam- Claims. (Cl. 172-36) and engaging the ground end surface of thelatter.

A cupped thrust plate 2l is secured to a bearing block 22 by means ofrivets 23 and the cupped eter substantially equal to that of the shaftI6 portion of the plate nesting the ball 20 and retaining the latter inposition wherein it engages.

not only the plate and shaft, but the inner surface of the bearingsleeve I'I. During rotation of the shaft the ball which is free torotate will be continuously turning in various directions as de-ltermined by the changing stresses on it and therefore the wearing of theball will take place uniformly, thus providing a stur`dy bearingstructure having a long life.

The improved armature and commutator assembly of the present inventionis provided wherein the lead wires from the armature coils IIIb may besecurely bound at the points where they extend from the coils to thecommutator II, thereby preventing loosening of the leads throughout theuseful life of the motor.

As shown in the drawing, the commutator II which is of the disk typecomprises a molded hub II a having embedded metal segments IIb to whichthe armature leads Ille are soldered. The molded hub Ila in thecommutator is provided with an integral skirt IIc extending toward thearmature laminations Ilia and enclosing a portion of the windings Ilib.

The armature lead wires I 0c extend from the coils IIlb at a pointsubstantially directly opposite to the periphery of the skirt llc,overlie the skirt and pass to the commutator segments IIb. Thus it willbe seen that the wires, extending through the shortest path possible tothe commutator, will have a minimum length. This tends to minimize theflexing of the wire due to centrifugal force as the motor accelerates ordecelerates. The lead wires Ic are'securely bound to the skirt llc by astrip of adhesive tape or equivalent binding 24 which is wrapped aroundthe wires and the skirt to bind the wires securely thereto. When tapelis used, it is preferable that it be lapped on itself for approximatelyone-half turn to securely fasten the leads in position. At the time thatthe armature assembly is completed, including the placing of the tape24, the entire assembly is dipped in varnish and baked, thereby causingthe binding to be securelyheld in place. The leads thus securely boundagainst the skirt l Ic eliminate unsupported stretches of wire whichmight, as a result of severe vibrations during continued use of themotor, ultimately break free from the commutator segments or because offatigue in the Wire resulting from vibrations and exing thereof duringthe operation of the mo- 3 torwili cause abreakageinthewireandafaiiureof the motor.

Variations and modifications may be made within the scope of thisinvention and portions of the improvements may be used without others.

I claim: 1. In an electric m'otor, a rotatable armature,

including a shaft, and a commutator and windings coaxially mounted onthe shaft; a cylindrical member of rigid insulating material rigidlysecured to said shaft between the said commutator and windings; leadwires extending from the windings exteriorly past the periphery of thecylindrical member to the commutator; and a tape binding the lead wiresagainst said periphery to prevent dislocation of said wires.

2. In an electric motor, a rotatable armature including a commutator andwindings disposed axially of the commutator, wound on magnetic coremeans and having a portion of substantially convex shape extended towardthe commutator; a band of rigid insulating material rigidly secured tothe commutator, extending about the said convex portion of the windingsto protect same, said band having an external peripheral portion locatedbetween the commutator and the core means; lead wires extending from thewindings past the peripheral portion of the insulating band to thecommutator; and means for binding the lead wires against the saidperipheral portion of the band to prevent disloca tion of said wires.

3. The invention as dened in claim 2, in which the commutator comprisesa hub of rigid insulating material and metallic segments embedded :nsaid hub, and in which the band of insulating material is integral withthe said hub.

' 4. In an electric motor, a rotatable armature including windings. anda combined commutator and lead support element disposed axially o! saidwindings, said element comprising conductive segments embedded in ablock ot insulating material to form a commutator, and a rigidinsulating band .integrally formed with the material oi' said block andextending between said commutator and said windings; lead wiresextending from the windings past the cylindrical band to the conductivesegments; and means for binding the lead wires against the insulatingband to prevent dislocation of said wires.

5. In an electric motor, a rotatable armature. including n. disccommutator having lead connection points spaced radially from its centerof rotation, said armature including windings disposed axially of saidcommutator and having an end portion of reduced diameter projectingtowards the commutator; a cylindrical band of rigid insulating material;means rigidly securing the band to the commutator between the saidcommutator and windings, said band having a portion which surrounds theend portion of reduced diameter; lead wires extending from the windingspast the cylindrical band to said connection points, and means forbinding the lead wires against the insulating band to preventdislocation of said wires.

WlLLIAM F. ALLENBY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PA'I'ENTS Number Name Date 2,l88,170 Zschau Jan. 23, 19402,283,803 Humphrey May 19, 1942

